1. Field of the Invention
This invention relates generally to an image processing apparatus and more particularly to an image processing apparatus having a plurality of nodes with access to disk storage.
2. Discussion of the Background
Advances in computer technology have allowed many problems to be solved due to the continuing increase in the power, size and speed of computing systems. In some areas, such as image processing, any advance in speed and power of the computer or decrease in cost is welcome due to the complexity of the problems solved.
One advance which has recently been helpful in this area is the use of pipeline processor devices. Such a device is shown in U.S. Pat. No. 4,464,788. The use of such pipeline processing systems speeds up the processing of the image. Other examples of pipeline processors are shown in U.S. Pat. Nos. 4,101,960, 4,620,275 and 4,621,399.
Another typical type of image processor is shown in FIG. 1. The system is used as a peripheral device 12 which is connected to a host such as a workstation 10 or similar computer. The workstation is connected through an adapter 14 to a local bus 26 of the peripheral. Also connected to this bus are a series of nodes 24 which process the image, a disk controller 18 which controls a storage disk 20, a RAM 22 and a host CPU 16. While this system has many improvements over earlier devices, it is limited in that only the host CPU or workstation 10 (but not both) has direct access to the disk. This means that the speed at which information is moved from the disk to the various nodes is limited. It also means that a relatively complex input/output program must be written by the programmer to control the movement of this information. Another limitation is that the RAM must be relatively large to accommodate this system.
Some improvement can be made over this system by utilizing a virtual memory adaptation. That is, the disk and RAM operate together under the control of the host CPU using a virtual memory addressing scheme. This allows the RAM to be smaller, thus decreasing the cost of the device. However, the other problems described above still remain.